10,527 research outputs found
Uniaxial and biaxial soft deformations of nematic elastomers
We give a geometric interpretation of the soft elastic deformation modes of
nematic elastomers, with explicit examples, for both uniaxial and biaxial
nematic order. We show the importance of body rotations in this non-classical
elasticity and how the invariance under rotations of the reference and target
states gives soft elasticity (the Golubovic and Lubensky theorem). The role of
rotations makes the Polar Decomposition Theorem vital for decomposing general
deformations into body rotations and symmetric strains. The role of the square
roots of tensors is discussed in this context and that of finding explicit
forms for soft deformations (the approach of Olmsted).Comment: 10 pages, 10 figures, RevTex, AmsTe
Lunar highland rock types: Their implications for impact induced fractionation
The first step in a petrologic study must be a classification based on observed textures and mineralogy. Lunar rocks, may be classified into three major groups: (1) coarse-grained igneous rocks, (2) fine-grained igneous rocks and (3) breccias. Group 1 is interpreted as primitive lunar crustal rocks that display various degrees of crushing and/or annealing. Group 2 is interpreted as volcanic rocks. Group 3 is interpreted as resulting from impacts on the lunar surface and is subdivided on the basis of matrix textures into fragmental breccias, crystalline breccias that have been annealed, and crystalline breccias with igneous matrices. A synthesis of the relevant data concerning lunar highlands polymict breccias from the fields of petrography, chemistry, photogeology, and impact studies compels the prediction that the breccias should have homogeneous matrices from rock to rock within regions of the highlands of limited size where impact mixing has been efficient and extensive
Introduction to the Apollo collections: Part 2: Lunar breccias
Basic petrographic, chemical and age data for a representative suite of lunar breccias are presented for students and potential lunar sample investigators. Emphasis is on sample description and data presentation. Samples are listed, together with a classification scheme based on matrix texture and mineralogy and the nature and abundance of glass present both in the matrix and as clasts. A calculus of the classification scheme, describes the characteristic features of each of the breccia groups. The cratering process which describes the sequence of events immediately following an impact event is discussed, especially the thermal and material transport processes affecting the two major components of lunar breccias (clastic debris and fused material)
Response and encoding factors in ignoring irrelevant information
Subjects classified either the numerosity or numeric value of elements in successive stimulus displays. In separate experiments, responses were indicated by oral naming, card sorting, manual tapping, and oral tapping. Incongruent levels of numeric value slowed naming and sorting, but not tapping, when numerosity was the cue for responding. Incongruent numerosity slowed tapping, but not naming and sorting, when numeric value was the cue. Changes in stimulus response mapping may thus critically alter the ability to ignore an irrelevant stimulus dimension
Response and encoding factors in ignoring irrelevant information
Subjects classified either the numerosity or numeric value of elements in successive stimulus displays. In separate experiments, responses were indicated by oral naming, card sorting, manual tapping, and oral tapping. Incongruent levels of numeric value slowed naming and sorting, but not tapping, when numerosity was the cue for responding. Incongruent numerosity slowed tapping, but not naming and sorting, when numeric value was the cue. Changes in stimulus response mapping may thus critically alter the ability to ignore an irrelevant stimulus dimension
Symmetries and Elasticity of Nematic Gels
A nematic liquid-crystal gel is a macroscopically homogeneous elastic medium
with the rotational symmetry of a nematic liquid crystal. In this paper, we
develop a general approach to the study of these gels that incorporates all
underlying symmetries. After reviewing traditional elasticity and clarifying
the role of broken rotational symmetries in both the reference space of points
in the undistorted medium and the target space into which these points are
mapped, we explore the unusual properties of nematic gels from a number of
perspectives. We show how symmetries of nematic gels formed via spontaneous
symmetry breaking from an isotropic gel enforce soft elastic response
characterized by the vanishing of a shear modulus and the vanishing of stress
up to a critical value of strain along certain directions. We also study the
phase transition from isotropic to nematic gels. In addition to being fully
consistent with approaches to nematic gels based on rubber elasticity, our
description has the important advantages of being independent of a microscopic
model, of emphasizing and clarifying the role of broken symmetries in
determining elastic response, and of permitting easy incorporation of spatial
variations, thermal fluctuations, and gel heterogeneity, thereby allowing a
full statistical-mechanical treatment of these novel materials.Comment: 21 pages, 4 eps figure
Determination of surface resistance and magnetic penetration depth of superconducting YBa2Cu3O(7-delta) thin films by microwave power transmission measurements
A novel waveguide power transmission measurement technique was developed to extract the complex conductivity of superconducting thin films at microwave frequencies. The microwave conductivity was taken of two laser ablated YBa2Cu3O(7-delta) thin films on LaAlO3 with transition temperatures of approx. 86.3 and 82 K, respectively, in the temperature range 25 to 300 K. From the conductivity values, the penetration depth was found to be approx. 0.54 and 0.43 micron, and the surface resistance (R sub s) to be approx. 24 and 36 micro-Ohms at 36 GHz and 76 K for the two films under consideration. The R sub s values were compared with those obtained from the change in the Q-factor of a 36 GHz Te sub 011-mode (OFHC) copper cavity by replacing one of its end walls with the superconducting sample. This technique allows noninvasive characterization of high transition temperature superconducting thin films at microwave frequencies
When and where do you want to hide? Recommendation of location privacy preferences with local differential privacy
In recent years, it has become easy to obtain location information quite
precisely. However, the acquisition of such information has risks such as
individual identification and leakage of sensitive information, so it is
necessary to protect the privacy of location information. For this purpose,
people should know their location privacy preferences, that is, whether or not
he/she can release location information at each place and time. However, it is
not easy for each user to make such decisions and it is troublesome to set the
privacy preference at each time. Therefore, we propose a method to recommend
location privacy preferences for decision making. Comparing to existing method,
our method can improve the accuracy of recommendation by using matrix
factorization and preserve privacy strictly by local differential privacy,
whereas the existing method does not achieve formal privacy guarantee. In
addition, we found the best granularity of a location privacy preference, that
is, how to express the information in location privacy protection. To evaluate
and verify the utility of our method, we have integrated two existing datasets
to create a rich information in term of user number. From the results of the
evaluation using this dataset, we confirmed that our method can predict
location privacy preferences accurately and that it provides a suitable method
to define the location privacy preference
Revitalization in a scattered language community: Problems and methods from the perspective of Mutsun language revitalization
This article addresses revitalization of a dormant language whose prospective speakers live in scattered geographical areas. In comparison to increasing the usage of an endangered language, revitalizing a dormant language (one with no living speakers) requires different methods to gain knowledge of the language. Language teaching for a dormant language with a scattered community presents different problems from other teaching situations. In this article, we discuss the types of tasks that must be accomplished for dormant-language revitalization, with particular focus on development of teaching materials. We also address the role of computer technologies, arguing that each use of technology should be evaluated for how effectively it increases fluency. We discuss methods for achieving semi-fluency for the first new speakers of a dormant language, and for spreading the language through the community
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